This invention relates in general to methods and apparatus for processing, compression, and/or transmission of data based upon quantum properties. Quantum properties include quantum entanglement and quantum teleportation of information, which is linked to the property of quantum entanglement. Quantum entanglement can exist between any two quantum systems such as between two photons, two atomic/ionic systems, or between a photon and an atom/ion based quantum system. The prior art system depicted in FIG. 1A is a layout for the demonstration of the Duan, Lukin, Cirac and Zoller (DLCZ) protocol 1 wherein laser beams through atomic ensembles L and R generate optical fields 1 and 2 from spontaneous Raman scattering. These optical fields 1 and 2 interfere on a Beam Splitter BS resulting in L and R atomic ensembles becoming entangled. A Bell state measurement is performed with detection by detectors D1 and D2. In FIG. 1B a phase stable scheme is proposed for entangling distant atomic ensembles through two-photon Hong-Ou-Mandel type interference. Note that a Bell state measurement is depicted in the center of FIG. 1B.
Quantum communications may sometimes be used in conjunction with compression techniques involving the usage of qubits, as shown in FIGS. 2A-2D. Qubits are units of quantum information that may be visualized by a state vector in a two-level quantum-mechanical system. Unlike a binary classical bit, a qubit can have the values of zero or one, or a superposition of both. A qubit may be measured in basis states (or vectors) and a conventional Dirac symbol is used to represent the quantum state values of zero and one herein, as for example, |0 and |1. For example, on a physical qubit this may be implemented by assigning the value “0” to a horizontal photon polarization and the value “1” to the vertical photon polarization. The “pure” qubit state is a linear superposition of those two states which can be represented as a combination of |0 and |1 or qk=Ak|0+Bk|1, or in generalized form as An|0 and Bn|1 where An and Bn represent the corresponding probability amplitudes and An2+Bn2=1. FIG. 2A is a diagrammatic visualization of a three-qubit quantum binary tree, which has an information storage index space equivalency to eight classical bits; i.e., 3 qubits provide an index space of 8. Unlike classical bits, a qubit can exhibit quantum properties such as quantum entanglement, which allows for higher correlation than that possible in classical systems. A pair of photons which are entangled can be referred to as an entangled photon pair. When one photon of an entangled photon pair is measured, the determination of the state of that photon (such as polarization or angular momentum) in effect determines the state of the other photon of the entangled photon pair, since entangled photon pairs are the conjugates of one another. In this example, each photon of the entangled pair may be considered a half of the entangled photon pair.